What model motherboard do you have? Do you know if it has any on board USB headers, for adding additional USB ports? You will have to check the specifications for each device that you are intending on attaching to your system, and then check the specs on your motherboard to see what your tolerances are.

As for hubs some are better than others, you can look into using powered hubs, but then you have to worry about powering the hub. Most of the hubs I have seen are 5v so you can get away with powering from your power supplies 5v rail, but make sure you know what you are doing. There are also self powered or bus powered hubs that require no additional power supply aside from the USBs power. If you go this route you will have to know what your current draw is and see if your motherboard can hack it.

Again I think we would need more information on what motherboard and processor you intend on using, along with any drives, etc. before starting to guess whether or not either of the power supplies you mentioned would work. Let me know what you have to work with and I will try my best to help you answer your question.

And before DarquePervert tells you, like he told me... SEARCH, Search can be your best friend. I know you will read it all over on here, but seriously I found there was so much information already out there, and most every subject that I can think of there is probably a thread on here for. I hope I can / did help.

Your board should have one in board USB header for 2 usb ports. The bracket should be provided with your board. If it's possible in your setup I would definetly use this bracket for stability reasons. It depends on what type of HQCT you plan to install but if you use the first version of it, it will use this header so in that case it won't be available anymore.

You can also add an usb hub. Many hubs have problems though with external harddisks and are also not very reliable when using hibernation/standby modes. It helps if you power the hub. You can use the 5V rail of your M2 ATX for this in most cases. Make sure what voltage your hub is but most of them are 5V.

The M2 ATX is a good option for your setup. It has plenty of power for it. I use an M1 ATX for pretty much the same setup with an additional Soundblaster Extigy powered by it and an external HD also powered by the M1. With an M2 ATX you will not run out of power soon even when in the future you want to add some things to your install.